Introduce the KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY attribute to create a "fixed-counters-only" PMU.
Much like KVM_ARM_VCPU_PMU_V3_IRQ and other read-write attributes, this attribute provides a getter that facilitates kernel and userspace debugging/testing. Signed-off-by: Akihiko Odaki <[email protected]> --- Documentation/virt/kvm/devices/vcpu.rst | 32 ++++++++++++++++++++++++++++---- arch/arm64/include/uapi/asm/kvm.h | 1 + arch/arm64/kvm/pmu-emul.c | 26 +++++++++++++++++++++++++- 3 files changed, 54 insertions(+), 5 deletions(-) diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst index 5e3805820010..58a6639c0196 100644 --- a/Documentation/virt/kvm/devices/vcpu.rst +++ b/Documentation/virt/kvm/devices/vcpu.rst @@ -71,7 +71,8 @@ irqchip. -ENODEV PMUv3 not supported or GIC not initialized -ENXIO PMUv3 not properly configured or in-kernel irqchip not configured as required prior to calling this attribute - -EBUSY PMUv3 already initialized or a VCPU has already run + -EBUSY PMUv3 already initialized, a VCPU has already run or + FIXED_COUNTERS_ONLY has already been set -EINVAL Invalid filter range ======= ====================================================== @@ -113,14 +114,14 @@ using event 0x11 (CPU_CYCLES). :Returns: - ======= ==================================================== + ======= =========================================================== -EBUSY PMUv3 already initialized, a VCPU has already run or - an event filter has already been set + an event filter or FIXED_COUNTERS_ONLY has already been set -EFAULT Error accessing the PMU identifier -ENXIO PMU not found -ENODEV PMUv3 not supported or GIC not initialized -ENOMEM Could not allocate memory - ======= ==================================================== + ======= =========================================================== Request that the VCPU uses the specified hardware PMU when creating guest events for the purpose of PMU emulation. The PMU identifier can be read from the "type" @@ -162,6 +163,29 @@ explicitly selected, or the number of counters is out of range for the selected PMU. Selecting a new PMU cancels the effect of setting this attribute. +1.6 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY +------------------------------------------------------ + +:Parameters: no additional parameter in kvm_device_attr.addr + +:Returns: + + ======= ================================================== + -EBUSY PMUv3 already initialized, a VCPU has already run, + an event filter has already been set or + a hardware PMU has already been specified + -ENXIO Attempted to get before setting + -ENODEV Attempted to set while PMUv3 not supported + ======= ================================================== + +If set, KVM emulates PMUv3 without programmable event counters. Only fixed +counters are exposed to the guest: the cycle counter today, and the instruction +counter if support for FEAT_PMUv3_ICNTR is added. + +With programmable counters disabled, the VCPU can run on any physical CPU. +This is particularly useful on heterogeneous systems where different hardware +PMUs cover different physical CPUs. All VCPUs in a VM share this attribute. + 2. GROUP: KVM_ARM_VCPU_TIMER_CTRL ================================= diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index 1c13bfa2d38a..39a1a1e412e6 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -437,6 +437,7 @@ enum { #define KVM_ARM_VCPU_PMU_V3_FILTER 2 #define KVM_ARM_VCPU_PMU_V3_SET_PMU 3 #define KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS 4 +#define KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY 5 #define KVM_ARM_VCPU_TIMER_CTRL 1 #define KVM_ARM_VCPU_TIMER_IRQ_VTIMER 0 #define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1 diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c index 40cad183376c..ad9ff4d0d89c 100644 --- a/arch/arm64/kvm/pmu-emul.c +++ b/arch/arm64/kvm/pmu-emul.c @@ -1149,11 +1149,13 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id) arm_pmu = entry->arm_pmu; if (arm_pmu->pmu.type == pmu_id) { if (kvm_vm_has_ran_once(kvm) || + kvm_pmu_fixed_counters_only(kvm) || (kvm->arch.pmu_filter && kvm->arch.arm_pmu != arm_pmu)) { ret = -EBUSY; break; } + set_bit(KVM_ARCH_FLAG_PMU_V3_EXPLICIT, &kvm->arch.flags); kvm_arm_set_pmu(kvm, arm_pmu); cpumask_copy(kvm->arch.supported_cpus, &arm_pmu->supported_cpus); ret = 0; @@ -1164,6 +1166,22 @@ static int kvm_arm_pmu_v3_set_pmu(struct kvm_vcpu *vcpu, int pmu_id) return ret; } +static int kvm_arm_pmu_v3_set_pmu_fixed_counters_only(struct kvm_vcpu *vcpu) +{ + struct kvm *kvm = vcpu->kvm; + + lockdep_assert_held(&kvm->arch.config_lock); + + if (kvm_vm_has_ran_once(kvm) || kvm->arch.pmu_filter || + test_bit(KVM_ARCH_FLAG_PMU_V3_EXPLICIT, &kvm->arch.flags)) + return -EBUSY; + + set_bit(KVM_ARCH_FLAG_PMU_V3_FIXED_COUNTERS_ONLY, &kvm->arch.flags); + kvm_arm_set_nr_counters(kvm, 0); + + return 0; +} + static int kvm_arm_pmu_v3_set_nr_counters(struct kvm_vcpu *vcpu, unsigned int n) { struct kvm *kvm = vcpu->kvm; @@ -1238,7 +1256,7 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) filter.action != KVM_PMU_EVENT_DENY)) return -EINVAL; - if (kvm_vm_has_ran_once(kvm)) + if (kvm_vm_has_ran_once(kvm) || kvm_pmu_fixed_counters_only(kvm)) return -EBUSY; if (!kvm->arch.pmu_filter) { @@ -1283,6 +1301,8 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) return kvm_arm_pmu_v3_set_nr_counters(vcpu, n); } + case KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY: + return kvm_arm_pmu_v3_set_pmu_fixed_counters_only(vcpu); case KVM_ARM_VCPU_PMU_V3_INIT: return kvm_arm_pmu_v3_init(vcpu); } @@ -1309,6 +1329,9 @@ int kvm_arm_pmu_v3_get_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) irq = vcpu->arch.pmu.irq_num; return put_user(irq, uaddr); } + case KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY: + if (kvm_pmu_fixed_counters_only(vcpu->kvm)) + return 0; } return -ENXIO; @@ -1322,6 +1345,7 @@ int kvm_arm_pmu_v3_has_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr) case KVM_ARM_VCPU_PMU_V3_FILTER: case KVM_ARM_VCPU_PMU_V3_SET_PMU: case KVM_ARM_VCPU_PMU_V3_SET_NR_COUNTERS: + case KVM_ARM_VCPU_PMU_V3_FIXED_COUNTERS_ONLY: if (kvm_vcpu_has_pmu(vcpu)) return 0; } -- 2.55.0
